youtube-dl a portion of a video.

youtube-slice

#!/usr/bin/env python3

import shlex
import argparse
import youtube_dl
import subprocess as sp
from pathlib import Path
from youtube_dl.utils import sanitize_filename


USER_AGENT = "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"


def ffmpeg(args: list) -> None:
    "Base ffmpeg call."
    sp.call(shlex.split(f"ffmpeg -v quiet -y {args}"))


def slice_video(video_url, start, end, output="/tmp/ytslice.mp4", intact=False):
    "Get video info and then download and slice it"
    assert video_url, "Missing video, can't continue"
    assert start, "Missing `start`, can't continue"
    assert end, "Missing `end`, can't continue"
    title = ""
    output_dir = Path(output).parent
    YTDL_OPTS = {
        "quiet": True,
        "restrictfilenames": True,
        "writethumbnail": False,
        "ignoreerrors": True,
        "geo_bypass": True,
        "format": "mp4",
        "outtmpl": f"{str(output_dir)}/%(title)s.%(ext)s"
    }

    ext = "mp4"
    if output.endswith(".mp3"):
        YTDL_OPTS.update({
            "format": "bestaudio/best",
            "postprocessors": [
                {
                    "key": "FFmpegExtractAudio",
                    "preferredcodec": "mp3",
                    "preferredquality": "192",
                }
            ]
        })
        ext = "mp3"

    with youtube_dl.YoutubeDL(YTDL_OPTS) as ydl:
        youtube_dl.utils.std_headers["User-Agent"] = USER_AGENT
        ytdl_info = ydl.extract_info(video_url, download=False)

        title = ytdl_info.get("title")
        yt_file = sanitize_filename(title, True, False)
        yt_file = output_dir / f'{yt_file}.{ext}'
        tmp_output = output_dir / f'{yt_file}.tmp.{ext}'
        ydl.download([video_url])
        ffmpeg(
            f"-i '{yt_file}' -ss '{start}' -to '{end}' -async 1 -acodec copy '{tmp_output}'"
        )

        if intact or ext == "mp3":
            Path(tmp_output).rename(output)
        else:
            ffmpeg(
                f"-i '{tmp_output}' "
	        "-pix_fmt yuv420p -vcodec libx264 "
	        "-vf scale=640:-1 -acodec aac -vb 1024k "
	        "-minrate 1024k -maxrate 1024k -bufsize 1024k "
	        "-ar 44100 -ac 2 "
	        "-strict experimental -max_muxing_queue_size 1024 -r 30 "
                f"'{output}'"
            )
            Path(tmp_output).unlink()

        Path(yt_file).unlink()

    return title, output



if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("video", type=str, default="", help="Video URL")
    parser.add_argument(
        "-ss", type=str, default="00:00:00", required=True, help="Start time"
    )
    parser.add_argument(
        "-to", type=str, default="", help="End time"
    )
    parser.add_argument(
        "-o",
        "--output",
        type=str,
        default="/tmp/ytslice.mp4",
        required=False,
        help="Output file (Default: /tmp/ytslice.mp4",
    )
    parser.add_argument(
        "--intact",
        action="store_true",
        help="Don't re-encode the video."
    )

    args = parser.parse_args()

    if args.video:
        title, output = slice_video(args.video, args.ss, args.to, args.output, args.intact)
        print (f"Title: {title}\nFile: {output}")
    else:
        parser.print_help()